1. Field of the Invention
The present invention relates to a system for maintaining the freshness of an object of preservation. More particularly, the present invention relates to a system for maintaining freshness comprising an electrode made of a flexible conducting polymer.
2. Description of Related Art
The cell membrane of all organisms comprise free ions, e.g. K+, Na+, Cl−, Ca2. These free ions function as follows: i) they control the volume of the cell by generating an osmotic pressure that controls both the entrance of water into a cell as well as the amount of water present in a cell; ii) they play a key role in other metabolic processes, such as transduction processes; and iii) they generate a strong electric field of 107 V/m across the cell membrane. Ion flux via the cell membrane is generated by the concentration of free ions present within the cell membrane and the voltage which exists within the cell membrane.
The difference in the electrical potential of the cell membrane may be a sum of the contribution of all free ions present in the cell. When an external electrical field is supplied to an organism, two possible results can occur. First, when the external electric field is static, the polarization in the cell has a predetermined direction and size, and when the external electric field oscillates, the free ions are forced to vibrate. Second, when the external electric field is harmonic or alternating, the external electric field functions as a periodic force not only on all ions present in the plasma membrane but also on all ions present in a protein channel. The alternating external electrical field promotes all free ions to vibrate. When an amplitude of the oscillation of the ions is greater than a predetermined threshold, the oscillating ions may give an erroneous signal of “open and close signal” of the protein channel, i.e. a voltage-gated channel. This phenomenon may disrupt the electrochemical balance of the cell membrane, and which subsequently may hinder the entire function of the cell.
There are various theories concerning the mechanism by which an external electric field effects a microorganism. There are also many diverse methods described for controlling a microorganism by using an electric field. The above theories are generally directed to the following concepts. A high electric voltage shock generates a different electric potential on the inside of the cell membrane as compared to the electric potential outside of the cell membrane. When an electric potential difference of about 1 V occurs between the inside of the cell membrane and the outside of the cell membrane, the cell membrane is either destroyed or, is electrically shocked by the high intensity electric field. Thus, the cell membrane of the microorganism cell is irreversibly damaged or destroyed. In addition, a high intensity electric field may destabilize the double lipid layer of the membrane or the membrane proteins, and consequently the microorganism cell may be destroyed.
FIG. 1 is a diagram illustrating a prior art structure of an apparatus for maintaining freshness. Referring to FIG. 1, the apparatus for maintaining freshness includes electrode modules 100a and 100b, and an electric field supply module 110.
The electrode modules 100a and 100b, which correspond to an anode 100a and a cathode 100b respectively, face each other. The electrode modules 100a and 100b are located in a housing member 130 where an object of preservation 120 is located, and are electrically connected with the electric field supply module 110.
The electric field supply module 110 supplies a voltage to the anode 100a and the cathode 100b, generating an electric field comprising a predetermined frequency range between the anode 100a and the cathode 100b, and controlling the frequency range of a supplied voltage. The anode 100a and the cathode 100b may be a conductive material, any one of gold (Au), silver (Ag), nickel (Ni), chrome (Cr), copper (Cu), Suss (Stainless steel), and indium tin oxide (ITO). In addition, the housing member 130 provides a space where the object of preservation 120 is positioned, and an adiabatic member (a heat insulator) may be disposed between an interior wall and an exterior wall of the housing member 130.
In the prior art apparatus for maintaining freshness, as illustrated in FIG. 1, the distance between the object of preservation 120 and the electrode is comparatively great, the efficiency of generating an electric field may be reduced. Also, since the surface of the object of preservation 120 is located beyond the effective range of the electric field, a microorganism present in the object of preservation 120 may not be effectively controlled by the electric field. In addition, since the efficiency of generating the electric field is low, a significant amount of power is required to apply an electric charge to the surface of the object of preservation 120.
Further, the distance between the shelves is constant, but the size and the shape of the object of preservation constantly change. Accordingly, the effect of an electric field applied to the surface of the object of preservation may not be constantly and uniformly controlled.